ORGANIC ELECTROLUMINESCENCE DEVICE
An organic EL device includes a pair of electrodes and an organic compound layer between pair of electrodes. The organic compound layer includes an emitting layer including a first material and a second material. The second material is a fluorescent material. Singlet energy EgS(H) of the first material and singlet energy EgS(D) of the second material satisfy a relationship of the following formula (1). The first material satisfies a relationship of the following formula (2) in terms of a difference ΔST(H) between the singlet energy EgS(H) and an energy gap Eg 77K (H) at 77K. EgS ( H )> EgS ( D ) (1) Δ ST ( H )= EgS ( H )− Eg 77K ( H )<0.3(eV) (2)
1 . An organic electroluminescence device comprising:
a pair of electrodes; and
an organic compound layer interposed between the pair of electrodes, the organic compound layer comprising an emitting layer comprising a first material and a second material, wherein
the first material is represented by a formula (101) below,
the second material is a fluorescent material, and
the organic electroluminescence device exhibits a ratio of the luminous intensity due to delayed florescence relative to the total luminous intensity larger than 37.5%,
where: rings A, B, and C each are a substituted or unsubstituted five- to seven-membered ring comprising as a ring-forming atom an atom selected from a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom;
the ring A is fused with the ring B and the ring C is fused with the ring B;
the ring C is optionally fused with an additional ring;
Q represents a group represented by a formula (103) below; and
k is 1 or 2,
where: at least one of Y 1 to Y 6 is a carbon atom to be bonded to L;
one to three of Y 1 to Y 6 are a nitrogen atom(s);
the rest of Y 1 to Y 6 of the carbon atom bonded with L or the nitrogen atom is CAr 1 ;
Ar 1 is a substituted or unsubstituted aromatic hydrocarbon group;
when a plurality of CAr 1 are present, Ar 1 is mutually the same or different; and
L represents a single bond or a linking group.
2 . An organic electroluminescence device comprising:
a pair of electrodes; and
an organic compound layer interposed between the pair of electrodes, the organic compound layer comprising an emitting layer comprising a first material and a second material, wherein
the first material is represented by a formula (101) below,
the second material is a fluorescent material, and
the organic electroluminescence device exhibits a residual intensity ratio larger than 36.0% after the elapse of 1 μs after voltage removal in a transitional EL measurement, wherein, the residual intensity ratio is a ratio of the luminous intensity due to delayed fluorescence relative to the total luminous intensity after the elapse of 1 μs,
where: rings A, B, and C each are a substituted or unsubstituted five- to seven-membered ring comprising as a ring-forming atom an atom selected from a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom;
the ring A is fused with the ring B and the ring C is fused with the ring B;
the ring C is optionally fused with an additional ring;
Q represents a group represented by a formula (103) below; and
k is 1 or 2,
where: at least one of Y 1 to Y 6 is a carbon atom to be bonded to L;
one to three of Y 1 to Y 6 are a nitrogen atom(s);
the rest of Y 1 to Y 6 of the carbon atom bonded with L or the nitrogen atom is CAr 1 ;
Ar 1 is a substituted or unsubstituted aromatic hydrocarbon group;
when a plurality of CAr 1 are present, Ar 1 is mutually the same or different; and
L represents a single bond or a linking group.
3 . The organic electroluminescence device according to claim 1 , wherein
a half bandwidth of a photoluminescence spectrum of the first material is 50 nm or more.
4 . The organic electroluminescence device according to claim 1 , wherein
a half bandwidth of a photoluminescence spectrum of the first material is 75 nm or more.
5 . The organic electroluminescence device according to claim 1 , wherein
a difference ΔT between an energy gap Eg 77K (H) at 77K of the first material and an energy gap Eg 77K (D) at 77K of the second material satisfies a relationship of a formula (3) below,
Δ T=Eg 77K ( H )− Eg 77K ( D )≧0.6[eV] (3).
6 . The organic electroluminescence device according to claim 2 , wherein
a half bandwidth of a photoluminescence spectrum of the first material is 50 nm or more.
7 . The organic electroluminescence device according to claim 2 , wherein
a half bandwidth of a photoluminescence spectrum of the first material is 75 nm or more.
8 . The organic electroluminescence device according to claim 2 , wherein
a difference ΔT between an energy gap Eg 77K (H) at 77K of the first material and an energy gap Eg 77K (D) at 77K of the second material satisfies a relationship of a formula (3) below,
Δ T=Eg 77K ( H )− Eg 77K ( D )≧0.6[eV] (3).